Stabilization of metal contaminated chloromethyl benzenes



Unite Stats STABILIZATION F METAL CONTAMINATED CHLOROMETHYL BENZENES No Drawing. Filed May 21,1958, Ser. No. 736,717

18 Claims. (Cl. 260-651) The present invention relates to the inhibition of decomposition of a halogenated aromatic hydrocarbon through the addition thereto of a stabilizing amount of an alpha, omega diacetylenic hydrocarbon having more than eight carbon atoms; and more particularly relates to the stabilization of chlorinated xylenes and compositions containing chlorinated Xylenes by additionthereto of a stabilizing amount of an alpha, omega diacetylenic hy-- drocarbon having more than eight carbon atoms.

It is known that a chlorinated Xylene ina pure condition may be stored or shipped withlittle or no decomposition induced by exposure to air, light, heat, and/or moisture. However, in many instances, obtaining such high purity chlorinated xylenes in commercial production is not feasible, and it has been found that the chlorinated xylenes normally encountered in commerce are subject to some decomposition when in contact with conditions causing decomposition such as specks of rust, aluminum, dirt, air, light, heat, moisture, and the like. Hence, means for preventing or inhibiting this decomposition of chlorinated Xylenes and/or other chlorinated aromatic hydrocarbons generally associated therewith are highly desirable.

Previously, various stabilizers for chlorinated hydrocarbons have been employed. Some of these compounds that have demonstrated a degree of effectiveness are acetylenic alcohols, acetylenic others, straight chain acetylenic esters, monoacetylenic hydrocarbons, and monoacetylenic monoolefinic hydrocarbons.

Although these prior stabilizers enjoyed a certain amount of success, surprisingly, such materials are not satisfactory for the stabilization of chlorinated ,xylenes and specifically, alphachlorop-xylene, for various reasons. Acetylenic alcohols are highly effective for the stabilization of such chlorinated aliphatic hydrocarbons as perchlorethylene but are ineifective for the stabilization of chlorinated xylenes such as alpha-chloro-p-Xylene in that decomposition occurs .even though the alpha-chloro-p- Xylene contains relatively large quantities of :these compounds. Monoacetyienic monoolefinic hydrocarbons and straight chain acetylenic. esters. are unsatisfactory forthe same reasons.

In view of the fact that that above general stabilizers employed are unsatisfactory, it would leadto the conclusion that the compositions employed inthe stabilization of chlorinated xylenes, and the method of the stabilization are relatively selective and thereforethose stabilizers employed previously in the stabilization of chlorinated hydrocarbons such as carbon tetrachloride, perchlorethylene, tetrachloroethylene, and the like are not adaptable to the stabilization of chlorinated xylenes.

Therefore, it is the primary object of the present invention to provide a means for inhibiting. the decomposition of a halogenated aromatic hydrocarbon, specifically, a chlorinated Xylene.

Another objective is the ,provision of .an ,eflective method of stabilizing a composition comprising. essential- 1y a chlorinated xylene, e.g., alpha-chloro-p-xylene.

A further object of this invention, therefore, is to provide a new stabilizing composition of matter, and a composition including the new stabilizing composition which will be especially stable under the influence of .various decomposing effects and particularly the effect of contaminating metal ions and the like.

These and other objects will be apparent to those skilled in the art from the discussion hereinafter.

Unstabilized chlorinated aromatic hydrocarbons as obtained from the producer including such compounds as benzyl chloride, may be either in relatively pure or impure condition. For the most part, the purity of such chlorinated hydrocarbons depends upon their age, i.e., the length of time it has stood unstabilized after production without particular effort being made to prevent decomposition. Accordingly, a relatively impure halo aromatic hydrocarbon is found to be of limited utility for many industrial needs although further decomposition may be satisfactorily inhibited by using the stabilizers of the present invention. On the other hand some unstabilized halo aromatic hydrocarbons are relativelyfresh and correspondingly pure and usable. Such materials require only stabilization against furtherdecomposition in order to be satisfactory for a number of uses.

The present invention is described primarily in relation to chloro aromatic hydrocarbons of relatively high initialpurity. It should be understood, however, that the invention is not limited in applicability to substantially pure solvents but rather insofar as effecting stabilization against further decomposition is concerned, the present invention is efiective substantially equally in an impure or pure solvent.

Where the initial percentage of purity is not tolerable, the chlorinated hydrocarbon requires pretreatment of a nature such that the major proportion or substantiallyall of the impurities are removed prior to the additionof stabilizers so as to provide a material having a good initial level of acceptability for industrial needs. As noted above, some chlorinatedhydrocarbons may not require such pretreatment, although those skilled in the art will understand that preferably a solvent containingunwherein x is a number from 5 to about 20, inclusive.

Further, the invention is directed to such a composition including an additional ingredient. effective to exert a stabilizing action against the influences of light and other sources of decomposition. It will be understood that the invention is not limited to a particular light or other stabilizer, and that in general any Well known light or other stabilizers may be employed with the general purpose stabilizer of thislinvention.

A preferred embodiment of the present invention comprises a composition of matter .comprisingessentially a normally liquid chain-chlorinated xylene and a stabilizing amount of an alpha, omega-diacetylenic aliphatic hydro carbon having more than eight carbon atoms, i.e., 1,8- nonadiyne. This compositionisparticularly directed to 3, the prevention of decomposition due to contact with contaminating metal ions such as iron and aluminum ions.

The diacetylenic hydrocarbons employed in the practice of this invention are known and may be prepared by chemically reacting an alkali metal, notably sodium acetylide with the respective polymethylene dibromides in liquid ammonia. Typically, the reaction product is isolated through distillation at reduced pressure. The preferred stabilizer of the present invention, i.e., 1,8- nonadiyne, boils at 70-72 C. at 29 mm. Hg pressure.

As stated, a new class of stabilizers noted above, specifically 1,8-nonadiyne, have been found particularly effective in stabilizing alpha-chloro-p-xylene contaminated with minor amounts of metallic ions such as those produced by specks of rust or aluminum, both in the liquid and in the vapor phase. For the most part, the stabilizing effect has been found to be most pronounced and prolonged where pretreatment which destroys the greater part of the contaminating metallic ions has been resorted to prior to the addition to the stablilizing diacetylenic hydrocarbons.

The method of stabilizing the above chlorinated aromatic hydrocarbons comprises essentially contacting a major proportion of the halogenated aromatic hydrocarbon, i.e., the chlorinated xylenes, with a stabilizing amount of the alpha, omega-diacetylenic hydrocarbons of the present invention. It is preferred that the stabilizer be added at a stage after the initial preparation of the chorinated aromatic hydrocarbon, and that a stabilizing amount of the alpha, omega-diacetylenic hydrocarbon be combined, as noted above, e.g., in an amount from about 0.04% to 3% by weight of the chlorinated aromatic hydrocarbon, preferably, however, from about 0.250% to 1% by weight of the chlorinated xylene. The extremes within the indicated broad range are preferred where the amount of metallic ion impurities associated with the chlorinated hydrocarbons is unusually high or unusually low While the amounts within the intermediate preferred range are generally sufiiciently efiective where the purified chlorinated xylene contains not more than about 0.2% of the metallic impurities most common in commercial production.

The beneficial effects of the present invention may also be realized where a chlorinated xylene has been purified in a commercial operation and stabilized either with a high boiling point stabilizer, i.e., a stabilizer such as one having a higher boiling point than that of the chlorinated xylene, or with stabilizers which are more volatile than the chlorinated xylene. By removing such stabilizers, as by chemical reaction or the like, the thus-treated mass is then fractionally distilled to recover the chlorinated xylene fraction which may be combined with an alpha, omegadiacetylenic hydrocarbon as described above in an amount suflicient to effect stabilization whereby the chlorinated xylene is rendered especially suitable due to its stability for various chemical processes.

Those skilled in the art will appreciate that while the alpha, omega-diacetylenic hydrocarbons of the present invention and particularly 1,8-nonadiyne will be useful in the practice of the present invention, those materials having boiling points in the same general range as that of the chlorinated xylene employed will be especially desirable as they may be expected to have the property of going into the vapor phase with the solvent and returning with it to the liquid phase. This is especially significant in vapor phase process operations as well as in processes in which the chlorinated xylene may be recovered by distillation and reused.

In order that no difliculty will be encountered in practicing the present invention, it is desired to illustrate the method of preparing 1,8-nonadiyne contemplated for use in the invention.

1,8-NONADIYNE Thepreparation of this compound is disclosed in the Journal of the Chemical Society (1950), pages 3131 to 3135. Sodium acetylide is reacted with pentamethylene dibromide in approximately stoichiometric amounts in the presence of liquid ammonia. Upon reaction completion, the resultant product is isolated through vacuum distillation, the desired C H distilling at 70-72 C. at 29 mm. Hg pressure. This product is less than 5% soluble in water and greater than 5% soluble in acetone, cyclohexanone, and xylene; and has a refractive index at 20 of 1.4492.

In order that those skilled in the art may better understand the present invention and in what manner the same may be carried into effect, specific examples are provided below.

Example I In order to demonstrate the effectiveness of the compounds of the present invention, a procedure is carried out by which alpha-chloro-p-xylene is stabilized with 1,8- nonadiyne. In this test 25 ml. of alpha-chloro-p-xylene is placed in five 4-oz. clear glass container. 1,8-nonadiyne is added to the first three solutions in concentrations of 0.125%, 0.250%, and 0.500%, respectively. A metal contaminant comprising 50% iron powder and 50% iron oxide is then added to each of the containers in a concentration of from 0.01 g. to 0.5 g. per container. A series of five mixtures is made up in this manner, the latter two being employed as standardized checks.

Each of these solutions is allowed to stand at room temperature for 18 days in the presence of ordinary room. light whereupon each of the solutions is rated on a scale from 0 for colorless to 10 for black, denoting complete decomposition. Employing this procedure, the standard check solutions were completely black at the end of the period employed whereas the stabilized solutions were colorless receiving a rating of 0, thus demonstrating that 1,8-nonadiyne is singularly effective in the stabilization of alpha-chloro-p-xylene for a period of greater than 18 days.

Example II In order to evaluate the efiect of 1,8-nonadiyne as a light stabilizer for chlorinated xylene, the procedure given in Example I is carried out in essentially the same manner with the exception that no metallic contaminants are added, and the solutions are allowed to stand in or dinary window light. 1,8-nonadiyne is added in concentrations of 0.250% and 0.500%. After fourteen days, observations indicate the addition of stabilizer to the alpha-chloro-p-xylene affords complete stabilization at the concentrations tested, whereas the standard check exhibits a certain amount of decomposition.

While the invention has been described in terms of its use in connection with chlorinated xylenes, i.e., alphachloro-p-xylene, it is desired to point out that it is not to be thus limited. The invention extends to the stabilization of other similar chlorinated aromatic hydro- While there have been described various embodiments of the invention, the methods and products described are not intended to be understood as limiting the scope of the invention as it is realized that changes therein are possible, and it is further intened that each element. recited in any of the following claims is to be understood as referring to all equivalent elements for accomplishing substantially the same results in substantially the same or equivalent manner, it being intended to cover the invention broadly in whatever form its principle may be utilized.

What is claimed is:

1. A stabilized composition of matter comprising essentially a side-chain chlorinated aromatic hydrocarbon contaminated with metal ions in combination with a stabilizing amount of an alpha, omega-diacetylenic aliphatic hydrocarbon having more than 8 carbon atoms.

2. A stabilized composition of matter comprising essentially a side-chain chlorinated aromatic hydrocarbon contaminated with metal ions in combination with a stabilizing amount of an alpha, omega-diacetylenic aliphatic hydrocarbon of the structure:

wherein x is a number from 5 to 20.

3. A stabilized composition of matter comprising essentially a side-chain chlorinated aromatic hydrocarbon contaminated with metal ions with a stabilizing amount of an alpha, omega-diacetylenic aliphatic hydrocarbon having more than eight carbon atoms in combination with another stabilizer.

4. A stabilized composition of matter comprising essentially a side-chain chlorinated xylene contaminated with metal ions and a stabilizing amount of an alpha, omegadiacetylenic aliphatic hydrocarbon having more than eight carbon atoms.

5. A stabilized composition of matter comprising essentially a side-chain halogenated aromatic hydrocarbon contaminated With metal ions with a stabilizing amount of 1,8-nonadiyne.

6. A stabilized composition of matter comprising essentially a side-chain chlorinated aromatic hydrocarbon contaminated with metal ions with a stabilizing amount of 1,8-nonadiyne.

7. A stabilized composition of matter comprising essentially a side-chain chlorinated polymethylbenzene contaminated with metal ions with a stabilizing amount of 1,8-nonadiyne.

8. A stabilized composition of matter comprising essentially a side-chain chlorinated polymethylbenzene contaminated with metal ions with a stabilizing amount of 1,8-nonadiyne in combination with another stabilizer.

9. A stabilized composition of matter comprising essentially a side-chain chlorinated xylene contaminated with metal ions with a stabilizing amount of 1,8-nonadiyne.

10. A stabilized composition of matter comprising essentially alpha-chloro-p-xylene contaminated with metal ions with a stabilizing amount of 1,8-nonadiyne.

11. The method of stabilizing a side-chain chlorinated aromatic hydrocarbon contaminated with metal ions comprising essentially contacting said side-chain chlorinated aromatic hydrocarbon with a stabilizing amount of an alpha, omega-diacetylenic aliphatic hydrocarbon having more than eight carbon atoms.

12. The method of stabilizing a side-chain chlorinated aromatic hydrocarbon contaminated with metal ions comprising essentially contacting said side-chain chlorinated aromatic hydrocarbon with a stabilizing amount of an alpha, omega-diacetylenic aliphatic hydrocarbon of the structure:

wherein x is a number from 5 to 20 inclusive.

13. The method of stabilizing a side-chain chlorinated polymethylbenzene contaminated with metal ions comprising essentially contacting said side-chain chlorinated polymethylbenzene with a stabilizing amount of an alpha, omega-diacetylenic aliphatic hydrocarbon having more than eight carbon atoms.

14. The method of stabilizing a side-chain chlorinated xylene comprising essentially contacting said side-chain chlorinated xylene contaminated with metal ions with a stabilizing amount of an alpha, omega-diacetylenic hydrocarbon having more than eight carbon atoms.

15. The method of stabilizing a side-chain halogenated aromatic hydrocarbon contaminated with metal ions comprising essentially contacting said side-chain halogenated aromatic hydrocarbon with a stabilizing amount of 1,8-nonadiyne.

16. The method of stabilizing a side-chain chlorinated aromatic hydrocarbon contaminated with metal ions comprising essentially contacting said side-chain chlorinated aromatic hydrocarbon with a stabilizing amount of 1,8- nonadiyne.

17. The method of stabilizing a side-chain chlorinated polymethylbenzene contaminated with metal ions comprising essentially contacting said side-chain chlorinated polymethylbenzene with a stabilizing amount of 1,8- nonadiyne.

18. The method of stabilizing alpha-chloro-p-xylene comprising essentially contacting said alpha-chloro-pxylene contaminated with metal ions with a stabilizing amount of 1,8-nonadiyne.

References Cited in the file of this patent UNITED STATES PATENTS 1,097,145 Snelling May 19, 1914 

1. A STABILIZED COMPOSITION OF MATTER COMPRISING ESSENTIALLY A SIDE-CHAIN CHLORINATED AROMATIC HYDROCARBON CONTAMINATED WITH METAL IONS IN COMBINATION WITH A STABILIZING AMOUNT OF AN ALPHA, OMERGA-DIACETYLENIC ALIPHATIC HYDROCARBON HAVING MORE THAN 8 CARBON ATOMS. 